Files in this package

Content in the Dryad
Digital Repository is offered "as is." By downloading files, you agree
to the Dryad Terms of Service.
To the extent possible under law, the authors have waived all copyright
and related or neighboring rights to this data.

Title

MCC_tree

Downloaded

9 times

Description

Maximum Clade Credibility tree for 22 species included in this study, based on a multilocus species tree obtained with *BEAST. The node values include Bayesian posterior probabilities and the bars indicate 95% High Posterior Density (HPD) intervals. (Included as Supplementary Figure S2.)

AbstractCritical thermal limits are thought to be correlated with the elevational distribution of species living in tropical montane regions, but with upper limits being relatively invariant compared to lower limits. To test this hypothesis, we examined the variation of thermal physiological traits in a group of terrestrial breeding frogs (Craugastoridae) distributed along a tropical elevational gradient. We measured the critical thermal maximum (CTmax; n = 22 species) and critical thermal minimum (CTmin; n = 14 species) of frogs captured between the Amazon floodplain (250 m asl) and the high Andes (3800 m asl). After inferring a multi-locus species tree, we conducted a phylogenetically informed test of whether body size, body mass, and elevation contributed to the observed variation in CTmax and CTmin along the gradient. We also tested whether CTmax and CTmin exhibit different rates of change given that critical thermal limits (and their plasticity) may have evolved differently in response to different temperature constraints along the gradient. Variation of critical thermal traits was significantly correlated with species’ elevational midpoint, their maximum and minimum elevations, as well as the maximum air temperature and the maximum operative temperature as measured across this gradient. Both thermal limits showed substantial variation, but CTmin exhibited relatively faster rates of change than CTmax, as observed in other taxa. Nonetheless, our findings call for caution in assuming inflexibility of upper thermal limits, and underscore the value of collecting additional empirical data on species’ thermal physiology across elevational gradients.